Soil and water remediation method and apparatus for treatment of recalcitrant halogenated substances

ABSTRACT

Disclosed are methods, apparatuses and systems for the remediation of contaminated soils, groundwater, water, and/or waste using a combination of reagents. The disclosed methods may be used to treat various recalcitrant halogenated substances, such as perfluoroalkyls and polyfluoroalkyls. Particular combinations of reagents that may be used in the disclosed methods include but are not limited to: (1) persulfate, oxygen and ozone; (2) persulfate, salt, oxygen and ozone; (3) persulfate, phosphate, and/or oxygen; (4) persulfate, phosphate, oxygen and ozone; (5) persulfate, phosphate, salt and oxygen (6) persulfate, phosphate, salt, oxygen and ozone; (7) oxygen and salt; and (8) air and salt. The disclosed methods may enhance destruction of organic contaminants in the liquid phase and may also control the rate of aerosol or foam formation relative to the rate of chemical oxidation and/or reduction/transfer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of priority to U.S. application Ser. No.16/269,033, filed Feb. 6, 2019, titled “SOIL AND WATER REMEDIATIONMETHOD AND APPARATUS FOR TREATMENT OF RECALCITRANT HALOGENATEDSUBSTANCES” and U.S. Provisional Patent Application No. 62/627,101,filed Feb. 6, 2018, titled “SOIL AND WATER REMEDIATION METHOD ANDAPPARATUS FOR TREATMENT OF RECALCITRANT HALOGENATED SUBSTANCES” each ofwhich are incorporated by reference herein in their entireties.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under National Instituteof Health (NIH)/National Institute of Environmental Health Science(NIEHS) Grant Number 1R43ES028649-01 and Grant Number 2R44ES028649-02.The government has certain rights in the invention.

BACKGROUND

Highly recalcitrant halogenated substances, such as poly- andperfluoroalkyl substances (PFAS), are not readily degraded or destroyedby previously known chemical oxidation, chemical reduction, combinedchemical oxidation/reduction or bio-oxidation methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a combined in-situ andex-situ treatment process flow, in accordance with various embodimentsof the subject disclosure.

FIG. 2 shows the experimental results of Example 2 in which a solutioncontaining PFAS was treated with various agents and the concentration ofthe PFAS was measured over time.

FIG. 3 shows the experimental results of Example 5 in which oxygenatedbuffered persulfate was used to treat a solution containing PFAS, inaccordance with some example embodiments, and the concentration of thePFAS was measured over time.

FIG. 4 is a pie chart showing the disposition of PFAS (approximated byfluorine measurements) in Example 5 after two days of treatment withoxygenated buffered persulfate.

FIG. 5 is a schematic diagram illustrating an ex-situ treatment processflow in which extracted groundwater or slurry is treated, in accordancewith various embodiments of the subject disclosure.

DETAILED DESCRIPTION

The present disclosure relates to methods and apparatuses for theremediation of contaminated water and/or soil and, in particular, to thereduction of the concentration of organic compounds in water and/or soilsuch as the highly recalcitrant halogenated substances, such as poly-and perfluoroalkyl substances (PFAS), that are not readily degraded ordestroyed by other chemical oxidation, chemical reduction, combinedchemical oxidation/reduction or bio-oxidation methods. The methods andapparatuses described herein may, in some cases, also be effective forless recalcitrant organic compounds of concern.

Both State and Federal governments in the United States and thegovernments of other countries have regulations governing hazardousorganic and inorganic contaminants in the environment. Subsurface soiland groundwater contamination with organic and inorganic contaminantshas been of concern to State, Federal and foreign governments since the1970′s. Action levels and clean-up standards have been promulgated byboth State and Federal governments for numerous organic and inorganiccontaminants.

Regulated organic contaminants in the subsurface environment include,but are not limited to: polychlorinated biphenyls (PCBs); halogenatedvolatile organic compounds (CVOCs), such as tetrachloroethene (PCE),trichloroethene (TCE), trichloroethane (TCA), dichloroethene (DCE),vinyl chloride; fuel constituents such as benzene, ethylbenzene,toluene, xylene, methyl tert butyl ether (MTBE), tertiary butyl alcohol(TBA), polynuclear aromatic hydrocarbons (PAHs), ethylene dibromide(EDB); pesticides such as (but not limited to) DDT; herbicides such as(but not limited to) Silvex. Pharmaceuticals, personal care products,aqueous film-forming foam (AFFF), and coatings are other products thatalso may contain highly recalcitrant chemicals.

The State and Federal regulations that govern these contaminants in thesubsurface outline protocols for subsurface investigation to identifythe extent of contamination, identification of the human health andecological risk posed by the contaminants, development of remedialaction alternatives for reducing or eliminating any significant riskposed by the contaminants, and selection and implementation of remedialmeasures to achieve the remediation goals. More recently, the federaland state governments in the US and around the world have begun toregulate a set of new “emerging contaminants” based on discovery of thewidespread distribution in the environment and evidence of detrimentaltoxicological health effects. The new emerging contaminants includepoly- and perfluoroalkyl substances (PFAS); 1,4-dioxane, and others.Currently, toxicological data exists for two particular PFAS compounds,perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA). It isanticipated that toxicological health effects for other PFAS compoundswill become available in the near future and will most likely befollowed by regulatory standards at the federal and state levels.Federal (USEPA) provisional health advisory levels for drinking waterfor PFOS and PFOA have been set at 0.2 parts per billion (ppb) and 0.4ppb, respectively. Some European countries have established similarregulatory limits allowable in drinking water.

Perfluoroalkyl acids (PFAAs) were utilized in aqueous film-forming foams(AFFF) and are now detected at many fire training areas (FTAs)throughout the world. PFAAs commonly co-occur with other prioritypollutants, particularly volatile organic compounds in groundwater.PFAAs are anthropongenic compounds have a carbon chain backbone that isfully-fluorinated. PFAAs are primarily either perfluoroalkylcarboxylates (PFCAs) or perfluoroalkyl sulfonates (PFSAs). PFAAs are oneof the most stable organic compounds due to the strong fluorine-carbonbonds. Therefore, PFAAs are resistant to hydrolysis, photolysis, andaerobic and anaerobic biodegradation. The longer-chain PFAAs, such asperfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS),were commonly used in industrial and commercial processes. Due to duetheir oleophobic and hydrophobic properties, they were incorporated intonon-stick, waterproof, and fire-resistant materials, such as lubricants,paints, polish, food packaging and aqueous film-forming foams (AFFFs).PFOS and PFOA can migrate through terrestrial and marine environmentswith very little degradation. In addition, PFOS and PFOA may be also beproduced from PFAA-precursors in the environment via degradation orbiotransformation. PFOA and PFOS, and polyfluorinated PFAA-precursorcompounds have all been identified in groundwater and surface water.These compounds are expected to be mobile and persist in groundwater orsurface water years after use.

Many traditional in situ remediation strategies, such as in situchemical oxidation (ISCO), or bioremediation, are ineffective fortreatment of PFAAs, because of the strong stability and thosephysicochemical properties of PFAAs that make them recalcitrant. Ex situsorption-based remediation processes, such as granular activated carbon(GAC) adsorption and anionic resin filtration have had success intreating these compounds. When present, any VOC co-contaminants maycompete with PFAAs for sorption sites to potentially limit theapplicability of these technologies in the field. Recently,nanofiltration has shown promise for PFAA removal. Ex-situ(above-ground) remediation methods involving groundwater extraction andtreatment are significantly more costly than in situ methods. Ex-situremediation methods will require many years of operation until PFAAclean-up targets (ng/L) may be achieved.

Strong oxidizing agents are reported in the literature to treatcontaminated soil and water by chemically degrading hazardous chemicalsusing ISCO or ex-situ chemical oxidation (ESCO). However, there arefewer options for the chemical destruction of PFAS compounds bytraditional oxidation methods. More recent research indicates that“higher energy” advanced oxidation processes such as sonic enhancedozonation that combines two technologies sonication and ozonation may berequired for PFAA degradation. However, degradation of PFOA and PFOS hasbeen shown using ozone and ozone with peroxide under alkaline conditionsat pH 11.

Recent literature indicates that activated persulfate-based oxidation ofPFOA can be performed at relatively low temperatures of 20-40° C. Thissuggests that persulfate may have potential as an in situ treatmenttechnology for subsurface PFAA contamination.

Methodologies and Devices

The subject matter of this application may involve, in some cases,interrelated products, alternative solutions to a particular problem,and/or a plurality of different uses of a single system or article.

In some embodiments, an above ground (ex-situ) reactor is disclosed inwhich contaminated water, waste, and/or groundwater may be introducedalong with air, ozone, oxygen and optionally other oxidants to bothdestroy, breakdown, and/or defluorinate PFAS. In these and otherembodiments, PFAS may be physically removed from the water, waste and/orgroundwater by concentrating the PFAS into the bubbles/aerosols that canthen be trapped and collected. These processes (physical removal anddestruction/breakdown/defluorination of PFAS) can be performed eithersequentially (in any order) or simultaneously.

In other embodiments, an in-situ “reactor” is disclosed in which waterthat is oxygenated or ozonated (for example, by micro to nanobubbles) ortreated groundwater (for example, groundwater that is treated with salt,buffer and oxidants) is either injected into the groundwater (possiblyafter being recirculated) or formed in-situ by injecting the gas andforming the micro to nanobubbles in the groundwater aquifer to therebyoxidize, transform, breakdown and defluorinate PFAS in the groundwater.In some embodiments, a nanobubble generating device may be used. In someembodiments, cyclodextrin or another cyclic oligosaccharide may beinjected into the groundwater to facilitate removal of PFAS. In theseand other embodiments, the gas headspace above the groundwater tablecontaining the bubbles/aerosols and concentrated PFAS may also beremoved. Alternatively, this fluid recirculation could be performed in avertical recirculation well(s) or vapor stripping well(s).Alternatively, horizontal wells could be used with one or morehorizontal wells below the groundwater surface and one or more above thegroundwater surface in the unsaturated zone soil.

In one aspect a method of reducing the concentration of an organiccontaminant such as PFAS in soil is provided, the method comprisingintroducing persulfate, phosphate, and/or oxygen into a saturated zoneto oxidize, reduce, defluorinate or otherwise degrade at least a portionof the organic contaminant.

In another aspect a method of reducing the concentration of an organiccontaminant such as PFAS in soil is provided, the method comprisingintroducing persulfate, phosphate, and/or oxygen where the oxygen issupplied by oxygen gas or air into a saturated zone to oxidize, reduce,defluorinate or otherwise degrade at least a portion of the organiccontaminant with the gas inducing mixing of the oxidant to enhancecontact with the contaminant.

In another aspect a method of reducing the concentration of an organiccontaminant such as PFAS in water is provided, the method comprisingintroducing persulfate, phosphate, and/or oxygen into the water tooxidize, reduce, defluorinate or otherwise degrade at least a portion ofthe organic contaminant.

In another aspect a method of rendering the recalcitrant organiccontaminant more readily amendable to bioremediation by transforming therecalcitrant organic contaminant to biodegradable compounds.

In another aspect a method of reducing the concentration of organiccontaminants such as PFAS in concentrated waste is provided, the methodcomprising introducing persulfate, phosphate, and/or oxygen into thewastes to oxidize, reduce, defluorinate or otherwise degrade at least aportion of the organic contaminant.

In another aspect, a method of controlling the rate of foam or aerosolformation to the rate of chemical oxidation, reduction, defluorination,and/or other degradation of at least a portion of the organiccontaminant by controlling the gas phase pressure or vacuum, gas flowrate, gas bubble size and/or bubble density per volume solution with orwithout mechanical mixing is provided, the method comprising introducingpersulfate, phosphate, and/or oxygen and ozone at a pH greater than,equal to, or less than pH 5.0 in the soil to remove a portion of theorganic contaminant from soil. In some embodiments, cyclodextrin couldoptionally be added in addition to the oxidants to encapsulate somePFAAs and/or to control the rate of transfer to aerosol or foam orenhance removal of PFAAs from soil.

In another aspect, a method of controlling the rate of foam or aerosolformation to the rate of chemical oxidation, reduction, defluorinationor otherwise degradation of at least a portion of the organiccontaminant by controlling the water temperature, gas flow rate, wateragitation, gas phase pressure or vacuum, gas bubble size and/or bubbledensity per volume solution with or without mechanical mixing isprovided, the method comprising introducing persulfate, phosphate,and/or oxygen and ozone at a pH greater than, equal to, or less than pH5.0 in the water to remove a portion of the organic contaminant fromwater. In some embodiments, cyclodextrin could optionally be added inaddition to the oxidants to encapsulate some PFAAs and/or to control therate of transfer to aerosol or foam or enhance removal of PFAAs fromwater.

In another aspect, a method to oxidize, reduce, defluorinate orotherwise degrade at least a portion of the organic contaminant byintroducing oxygen and ozone gas to the foam and/or aerosol in the gasphase above the water is disclosed.

In another aspect, a method to oxidize, reduce, defluorinate orotherwise degrade at least a portion of the organic contaminant bycontrolling the gas flow rate, gas phase overhead pressure or vacuum inthe vicinity of the foam and/or aerosol above the water is disclosed.

In another aspect, a method of controlling the rate of foam or aerosolformation to the rate of chemical oxidation, reduction, defluorinationor otherwise degradation of at least a portion of the organiccontaminant by controlling the gas flow rate, gas bubble size and/orbubble density per volume solution without any mechanical mixing isprovided, the method comprising introducing persulfate, phosphate,and/or oxygen and ozone at a pH greater than, equal to, or less than pH5.0 in the waste to reduce the organic contaminant in the waste.

In another aspect, a method to oxidize, reduce, defluorinate orotherwise degrade at least a portion of the organic contaminant byintroducing oxygen and ozone gas to the foam and/or aerosol in the gasphase above the waste is disclosed.

In another aspect, a method to oxidize, reduce, remove, defluorinate orotherwise degrade at least a portion of the organic contaminant bycontrolling the gas phase overhead pressure or vacuum in the vicinity ofthe foam and/or aerosol above the waste is disclosed.

In another aspect, methods of in-situ aquifer flushing are disclosed inwhich water containing cyclodextrin or another cyclic oligosaccharide isinjected to subsurface soil and groundwater to enhance PFAS removal fromthe soil and groundwater as it passes through the soil matrix to ahydraulically downgradient groundwater extraction well (or a single wellpush-pull method may alternatively be used) where groundwater containingthe cyclodextrin-PFAS complex may be extracted and removed using methodsdescribed herein, including but not limited to ex-situ treatment usingthe “gas infusion” reactor, as herein described.

DETAILED DESCRIPTION

The following patents are herein incorporated by reference in theirentireties: U.S. Pat. Nos. 7,667,087, 8,049,056, and 9,409,216. In U.S.Pat. No. 7,667,087, a method and apparatus for destruction of organiccontaminants using persulfate, phosphate, peroxide, and ozone isdisclosed. In U.S. Pat. No. 8,049,056, a method for destruction oforganic contaminants using oxidants and the stabilization of ozone usingan oligosaccharide is disclosed. In U.S. Pat. No. 9,409,216, a methodfor destruction of organic contaminants using a cyclic oligosaccharideand persulfate is disclosed.

In some embodiments, methods for reducing the concentration of organic(halogenated or otherwise) compounds in soil, concentrated wastes, waterand/or groundwater is provided. Contaminated soil in the saturated zone,smear (i.e., capillary) zone and/or unsaturated zone can be remediatedto concentrations that meet local, federal or other mandated or chosenlevels. Water, groundwater and/or soil may be decontaminated in-situ orex-situ using the disclosed methods. Concentrated wastes may bedecontaminated ex-situ, for example in a reactor. The methods mayinvolve the introduction or co-introduction of oxidants, such aspersulfate, phosphate, and/or oxygen in combination, or a combination ofpersulfate, phosphate, other salts and/or oxygen with or without ozoneinto any of the saturated, unsaturated and/or smear zones. One or moreadditional oxidants, such as hydrogen peroxide or other peroxides mayalso be used in combination with the oxidant(s). Results show that theco-introduction of these species may provide greater benefits than usingthem independently.

FIG. 1 illustrates a combined in-situ and ex-situ treatment processflow, in accordance with various embodiments of the subject disclosure.Specifically, FIG. 1 shows an in-situ reactive zone or flushing zonetreatment method in which one or more reagents are introduced into thesoil or groundwater and groundwater is then extracted at a pointdownstream from the point of injection. In some embodiments, reagentsmay be introduced into the soil or ground water through a trench thatmay be filled with gravel below the ground water table. The trench mayor may not have sheeting walls on the sides of the trench extending fromground surface to the ground water table or below. In some examples, thetrench may be backfilled with soil or gravel or a solid phase extraction(SPE) agent from the ground surface to the top of the ground water tableor may not be. In some cases, the SPE agent may be, for example, silica,alumina or activated carbon (e.g, granular activated carbon). The SPEagent may be used to adsorb the PFAA aerosol. Ozone gas may beintroduced into the trench above the ground water table to chemicallyoxidize, defluorinate, or otherwise remove the PFAA in foam or aerosolabove the groundwater table. The ozone gas may be introduced toregenerate the SPE agent in-place. The pressure of the ozone gas may be1, 2, or 3 atmospheres or greater. In some embodiments, an air vacuummay be applied to the backfilled or un-backfilled trench above thegroundwater table to remove PFAA-containing foam or aerosol. In someparticular example embodiments, a cyclic oligosaccharide, for examplecyclodextrin, may be injected into the groundwater (with or withoutother reagents) to facilitate removal of contaminated materials. Afterin-situ treatment and/or removal, the groundwater may then optionally betreated by any type of desired ex-situ process, such as treatment in agas infusion tank device, as described in detail below.

FIG. 1 also illustrates an ex-situ treatment process in which extractedgroundwater is treated in a reactor above-ground. As shown in FIG. 1,ex-situ treatment of the extracted groundwater may include, in someembodiments, treatment with one or more of the following reagents:persulfate, a buffer (e.g., phosphate), ozone, oxygen, hydrogen peroxideand cyclodextrin. In some particular embodiments, a gas infusion tankreactor may be used for various ex-situ treatment processes. Anysuitable design may be used to implement a gas infusion tank reactor asdescribed herein. For example, in some cases, a gas infusion tankreactor may include one or more reaction compartments that are connectedin series, such that liquid flows from one reaction compartment to thenext once a certain volume of fluid accumulates in a reactioncompartment. Treatment reagents may be introduced to the fluid in onereaction compartment or in multiple reaction compartments. In someembodiments, reagents are injected into the bottom or a lower area ofthe reaction compartment(s). In some cases, gaseous reagents, such asoxygen or a combination of oxygen and ozone may be introduced into thesolution in the reactor. The gaseous reagents may be introduced as microbubbles and/or nano bubbles, in some embodiments. The hydraulicdetention time of the reactor may be any time and in some embodiments isat least 10 minutes, 30 minutes, at least 1 hour, at least 2 hours, atleast 4 hours, at least 8 hours, or at least 24 hours. Ozone gas at apressure of 1, 2, or 3 atmospheres may optionally be introduced abovethe water level in the reactor to contact the PFAA containing foamand/or aerosol in the gas phase to remove, de-fluorinate, or otherwisereduce its concentration. Alternatively or additionally, in some cases,an air vacuum may be applied to the gas phase to remove the PFAA foam oraerosol from the reactor. Either pressure or vacuum applied to the gasphase may be used to control the rate of foam and/or aerosol formationrelative to the rate of chemical oxidation in the liquid phase. Beforeor after ex-situ treatment, the extracted groundwater may, in somecases, be further treated, such as by activated carbon filtration orother treatment methods.

It is to be understood that in some cases, the disclosed methods may beapplied either in-situ or ex-situ, or a combination or both in-situ andex-situ, depending on the desired application. The followingdescriptions are thus intended to apply to both in-situ and/or ex-situtreatment methods, except as otherwise explicitly stated.

In some embodiments, ozone gas is introduced above the water into thegas phase where PFAA containing foam and/or aerosol may be formed toprovide chemical oxidation, reduction, defluorination or otherdegradation of at least a portion of the organic contaminant.

In some embodiments, the gas phase may be pressurized or placed undervacuum to assist with controlling the rate of foam and or aerosolformation relative to the rate of chemical oxidation, reduction,defluorination or other degradation of the organic contaminant in thewater.

Different types of soils may be treated according to the disclosedmethods, including, for example, sand, rock, sediment, loam and clay.Waters that can be treated include, for example, groundwater, wastewater, process water and runoff.

Organic contaminants that may be remediated include but are not limitedto, halogenated substances, including poly- and perfluoroalkylsubstances (PFAS), organic (halogenated or otherwise) compounds (VOCs),semi-volatile organics (SVOC' s) polychlorinated biphenyls (PCBs);chlorinated volatile organic contaminants (CVOCs), benzene,ethylbenzene, toluene, xylene (BTEX), methyl-tert-butyl ether (MTBE),tertiary butyl alcohol (TBA), polynuclear aromatic hydrocarbons (PAHs),ethylene dibromide (EDB); pesticides and herbicides such as DDT andSilvex, tetrachloroethene (PCE), trichloroethene (TCE), trichloroethane(TCA), dichloroethane (DCA), methylene chloride, carbon tetrachloride,dichloroethene (DCE), vinyl chloride, light non-aqueous phase liquids(LNAPL) and fuels such as gasoline, diesel fuel, fuel oils (including#2, #4 and #6), jet fuels (e.g., JP4 and JP5). Pharmaceuticals, personalcare products (PCP), endocrine disruptors and waste containing theseorganic contaminants may also be remediated.

In some aspects, methods and systems are provided for reducing theconcentration of organic (halogenated or otherwise) compounds in soiland/or groundwater. Oxidants, such as persulfate, phosphate, and/oroxygen in combination or a combination of persulfate, phosphate, othersalts and/or oxygen with or without ozone may be introduced into thesaturated zone, resulting in an area of influence around the injectionpoint in which organic contaminants are oxidized, reduced, defluorinatedor otherwise destroyed and therefore reduced in concentration at leastin part. Below the area of influence, oxygen gas sparging can beintroduced into the saturated zone creating both mounding and a mixingzone and further contact between the persulfate, phosphate, and/oroxygen in the smear zone and saturated zone. Enhanced bioremediation ina saturated zone may occur after chemical oxidation of the contaminantsoccurs due to the residual sulfate, phosphate, and oxygen.

In select embodiments, reactants may be added to the contaminant tochemically alter the contaminant in the liquid phase. However, in otherembodiments, the reaction conditions may be selected to urge thecontaminant from the liquid phase into an aerosol and/or foam. While insuch embodiments, some chemical destruction of the contaminant may occurin the liquid phase, an appreciable amount of contaminant may bephysically transferred to an aerosol/foam without being chemicallyaltered. In some of these embodiments, the resulting aerosol and/or foammay be further treated to destroy or isolate contaminants present in theaerosol/foam. For example, in some embodiments, one or more gases may beintroduced to a reactor via a nanobubble diffuser or other nanobubblegenerating device positioned in contaminated water or groundwater. Thereactor may have headspace above the fluid that allows the aerosol/foamto be collected and passed through a trap (to collect the contaminantsin a much more concentrated form) before discharge of the gas to theatmosphere. In such embodiments, at least one the following removalprocesses may occur: (a) physical transfer of the surfactant- like PFASvia oxygen and/or ozone bubbles and aerosols from the aqueous (fluid)phase to the gas phase where they can be collected and concentrated in atrap; (b) oxidation, transformation, breakdown and defluorination of thePFAS by oxygen in the nanobubbles formed in the aqueous phase; (c)oxidation, transformation, breakdown and defluorination of the PFAS byozone in the nanobubbles formed in the aqueous phase; and (d) oxidation,transformation, breakdown and defluorination of the PFAS by ozone in thebubbles and aerosols in the gas phase.

Gaseous reagents may be dissolved in an aqueous system or may beotherwise introduced to the contaminant. Any gas or gas mixture may beintroduced to the contaminant, such as air, nitrogen, oxygen, ozoneand/or nitrous oxide. In some embodiments, one or more gaseous reagentsare introduced in the form of nano bubbles or micro bubbles. In someembodiments, gaseous reagents may be introduced both in dissolved formand in the form or micro and/or nano bubbles. As used herein, the term“nano bubble” refers to a gas bubble having a diameter of less than 1.0micron and the term “micro bubble” refers to a gas bubble having adiameter of between 1.0-100 microns. In some embodiments, increasing thebubble size of gaseous reagents will decrease aerosol formation, whilein other embodiments, increasing bubble size will increase aerosolformation. Accordingly, the size of the gaseous bubbles may be adjustedto either increase or reduce aerosol formation, depending on the desiredlevel of aerosols.

In particular embodiments, one or more gaseous reagents having anaverage bubble size (diameter) of less than 50 microns, less than 40microns, less than 30 microns, less than 20 microns, less than 10microns, less than 1 micron, less than 0.8 micron, less than 0.6 micron,less than 0.4 micron, less than 0.2 micron, less than 0.1 micron, orless than 0.05 micron may be used. In other embodiments, gaseousreagents having an average bubbles size of at least 0.05 micron, 0.1micron, 0.2 micron, 0.4 micron, 0.6 micron, 0.8 micron, 1.0 micron, 10microns, 20 microns, 30 microns, 40 microns, or 50 microns may be used.

The bubble size of gaseous reagents can be selected based at least inpart on the ionic strength of the oxidant solution, the pH of thesolution, the total dissolved solids (TDS) of the solution, thetemperature of the solution and/or the concentration of the targetcompound(s). For example, in some embodiments, effective transport ofoxygen and/or ozone bubbles may be accomplished with a bubble size ofless than 1 micron, less than 10 microns, or less than 20 microns.

In some embodiments, the rate of chemical reaction of the contaminant inrelation to physical transfer of the contaminant to an aerosol and/orfoam may be controlled by altering one or more reaction conditions. Forexample, in some embodiments, any number of the following reactionconditions may be adjusted to change whether contaminants are treated inthe aqueous phase or are physically transferred to an aerosol/foam.Reaction conditions that may be adjusted include, but are not limitedto: the pressure of the reactor, the pressure of introduced gas, theflow rate of introduced gas, the percent ozone in introduced gas, theaverage gas bubble size, the range of gas bubble sizes, theconcentration of contaminant in the aqueous phase, the dimensions of thereactor, the depth of the aqueous solution, the extraction rate ofaerosol/foam in headspace, the pH of the solution, the concentration ofhydrogen peroxide, the concentration of persulfate present and the saltor buffer concentration.

In some embodiments, the pressure of one or more gaseous reagents may beselected to be within the range of 5 to 50 psi. In these and otherembodiments, the flow rate of one or more gaseous reagents may beselected to be within the range of 1 ml/minute to 1 cubic feet/hour persquare inch of the reactor in the horizontal direction and/or within arange of gas to liquid of 1% to 25%.

In various embodiments, the percent ozone concentration in a carriergas, such as oxygen, introduced in the reactor may be adjusted. Forexample, in some embodiments the percent ozone concentration in thecarrier gas (for example, oxygen gas) may be no more than 20%, withinthe range of 0-15%, within the range of 0-10% or within the range of0-5%.

In some embodiments, the dimensions of the reactor may be adjusted suchthat the reactor volume to reactor cross-sectional area perpendicular torising bubbles is either increased or decreased. For example, in someembodiments, the reactor may have a ratio of volume to cross-sectionalarea (m³/m²) perpendicular to rising bubbles that is within the range of1:1 to 1,000:1. In these and other embodiments, the pH of the aqueoussolution may be within the range of 4 to 10.5.

In various embodiments, reactants may be added to or removed from thereactor. For example, in some embodiments, the concentration of hydrogenperoxide in the reactor may be adjusted to be at least 1 ppm, at least 5ppm, at least 10 ppm, or greater than 10 ppm. In these and otherembodiments, the concentration of persulfate may be adjusted to bewithin the range of 1 to 100 g/L. In various embodiments, the persulfatemay be heated to a temperature above the temperature of the liquid phaseof the reactor. In some embodiments, the concentration of salt or otherbuffer present may be adjusted to be within the range of 0.1 to 10 g/L.

In some particular embodiments, containment may be removed from water,wastewater and/or soil in a multi-step process. For example, in someembodiments, a contaminant may be exposed to nanobubbles of a gas (suchas oxygen, air or nitrogen) in a solution having at least one ionicspecies present. In some such embodiments, the reaction conditions maytransfer the contaminant to an aerosol and/or foam that may becollected. Collection may be made, for example, using a water trap or asolid phase extraction using silica (e.g., Florisil) or alumina forinstance. The aerosol and/or foam may be more highly concentrated withcontaminant than the starting material. The more highly concentratedmaterial may then subsequently be treated, for example, by theintroduction of heated persulfate. The treatedwater/wastewater/soil/aerosol/foam may optionally be further treated byvarious processes. For example, additional oxidants, such as buffered orunbuffered oxygen, ozone and/or persulfate may be introduced to thematerial. In these and other embodiments, the material may be filteredthrough granular activated carbon (GAC) or other chemical filters toremove additional contaminant.

A salt such as sodium chloride or sodium persulfate may serve severalpurposes when used in the disclosed methods. For example, sodiumpersulfate may act as an oxidant, may increase ionic strength to aid inmaintaining a small bubble size, and/or may be used as a conservativetracer for hydraulic assessments along with specific conductance. Inthese and other embodiments, persulfate (either heated or unheated) maybe used to treat aerosols and/or foams that are formed in the reactor.

In some embodiments, methods are provided for reducing the amount ofhalogenated organic contaminants in a soil or water sample eitherin-situ or ex-situ. In some embodiments, at least a portion ofrecalcitrant organic contaminant present may be aerosolized, transferredto foam, and/or oxidized. “At least a portion” means at least some ofthe molecules present in the sample being treated will be oxidized. Forclarity, “at least a portion” does not mean that only a portion of aspecific molecule is oxidized. “Soil” as used herein includes soil,sediment, clay and rock.

It has been found that a combination of water soluble inorganicreagents, such as persulfate, phosphate, and/or oxygen in combination orpersulfate and phosphate in combination with oxygen and/or ozone mayprovide a level of compound destruction and/or transfer to aerosol/foamthat is superior to that of either one of the reagents used without theother, even at much greater concentrations. This data is surprising asprior to this discovery, it was believed that only extremely strongoxidizing agents, such as ozone, could effectively destroy recalcitrantorganic materials (e.g., halogenated organic contaminants). However, asdescribed in detail below, the disclosed methods may significantlyreduce the concentration of recalcitrant organic materials by usingoxidants with comparatively lower redox potentials (e.g., oxygen incombination with persulfate). It is believed that oxygen in combinationwith persulfate may form unidentified radical species responsible forthe degradation of PFAS.

It has also been found that a combination of water soluble inorganicreagents, such as persulfate, phosphate, and/or oxygen in combination,or persulfate and phosphate in combination with oxygen and/or ozone maytransform the surfactant like properties of some of the PFAS compoundsto render them less of a surfactant while making them more amenable tooxidation/reduction and defluorination.

In the disclosed methods of reducing the concentration of an organiccontaminant in soil, water, and/or waste, persulfate and oxygen gas maybe introduced to the organic contaminant to form an aerosol and/or foamcontaining PFAS. The disclosed methods may alternatively or additionallyoxidize at least a portion of the organic contaminant. In someembodiments, a buffer may also be introduced. For example, a phosphatebuffer may be used in some embodiments. However, in other embodiments, aphosphate buffer need not be present. In these and other embodiments, ahydrogen source may also be introduced. For example, in someembodiments, hydrogen gas may be introduced to the organic contaminantalong with the other reagents used. The disclosed methods may be capableof reducing the concentration of recalcitrant organic materials (e.g.,halogenated organic contaminants) by at least 50%, at least 60% at least75%, at least 80%, at least 90%, at least 95%, or at least 99%, in someembodiments. In some embodiments, the methods disclosed herein candestroy, or break down, greater than 50%, greater than 75%, greater than90%, greater than 95%, greater than 99% or greater than 99.9% of theperfluorinated materials that are present in a sample such as water,soil, waste water, waste streams or solvent systems. These levels ofPFAA removal via transfer to aerosol or foam or destruction can beobtained in less than 12 hours, less than six hours, less than two hoursor less than one hour of contact time. As used herein, the terms“destroy” and “break down” mean that the chemical structure of thecompound is altered. For example, a perfluoroalkyl acid is considered“destroyed” or “broken down” if one or more fluorine atoms are removedfrom the alkyl backbone of the original compound.

Persulfate is a preferred oxidant for remediating soil for severalreasons including that it has minimal reactivity with the soil itselfand therefore all, or most, of the oxidizing power of the reagent isavailable to oxidize organic contaminants. Persulfate may be along-lived oxidant, and this increased longevity can result in anincreased radius of influence and can help to minimize the requirednumber of injection points throughout the contaminated area. Persulfatemay be introduced to water or soil as a liquid, typically in the form ofan aqueous solution of sodium persulfate. Oxygen may be provided as agas, salt, or liquid for example, pure oxygen gas or air can be spargedinto the aqueous solution of persulfate and/or phosphate. In someembodiments, the pure oxygen or air may be passed through an ozonegenerator to introduce a mixture of ozone, typically up to 20 percentozone, with either oxygen or air into the aqueous solution. In someembodiments, oxygen can be supplied as a peroxide salt of calcium ormagnesium oxide. In other embodiments, oxygen can be supplied as aliquid by adding hydrogen peroxide. Hydrogen peroxide may be used insolution form and in some embodiments may be mixed with persulfate.

It is believed that use of oxygen or ozone in conjunction withpersulfate and/or phosphate may result in a high rate of conversion tooxidizing radicals that can provide for a wide radius of influence fromthe injection site. If hydrogen peroxide as a liquid form of oxygenaddition a high rate of conversion to oxidizing radicals may result andmay also contribute to a wide radius of influence. Without wishing to bebound by theory, additional sources of hydrogen may be helpful tofacilitate defluorination of the PFAS and corresponding breakdownproducts. For example, it is possible that the hydrogen (H) liberatedfrom the phosphate present (Na2HPO4) is used in a combinedoxidation/reduction reaction or that the HPO4 anion itself is used.

As will be appreciated in light of this disclosure, the disclosedmethods may present novel pathways to activate persulfate. For example,the disclosed methods of mixing oxygen and persulfate, either in thepresence of phosphate or without phosphate present, may prompt theformation of one or more sulfate radicals. The disclosed methods ofmixing ozone, oxygen, and persulfate, either in the presence ofphosphate or without phosphate present, may prompt the formation of oneor more sulfate radicals, hydroperoxide radicals, superoxide radicals,hydroxyl radicals, phosphate radicals, and/or phosphite radicals.

In some embodiments, a persulfate/phosphate mixture may be injected intowater, ground water (saturated zone), smear zone or unsaturated zone viaa first injector or injection well. A gas, such as oxygen gas alone orin combination with another gas (e.g., ozone), may be injected using thesame injector or injection well where they may or may not be in contactwith the other additives within the well. In some embodiments, a secondinjector may be used in the same region (or another region) as the firstinjector. Ozone may be formed on site by an in-situ or ex-situ ozoneproducing device(s) and in many cases may be mixed in oxygen or air to alevel of from about 1% to 20% by volume. Ozone in oxygen or air may besparged at rates that provide for a preferred radius of influence and insome cases the radius of influence may be at least as broad as that of aco-oxidant that may be introduced concurrently to the site. Feed ratesmay include, for example, 1-20 scfm per injection well. Together, theoxygen, ozone and/or persulfate (buffered with phosphate or unbuffered)may provide a combined radius of influence that provides greaterdestruction of compounds over a greater area than is realized usingeither compound independently, even when used independently at greaterconcentrations.

When treating ex-situ materials such as excavated soil, groundwater,waste water or process water, or concentrated wastes, methods ofintroducing reagents may be simplified and reagents such as oxidants andpH buffers may simply be added to the reactor at the desired time in theprocess. In some cases, the only reagents required are persulfate andoxygen and in other cases, the only reagents required are persulfate,oxygen and/or ozone and a source of phosphate ion. No other oxidants maybe required. However, in addition to oxygen, persulfate, and/orphosphate, other compounds may also be used to improve destruction ratesof co- contaminants in the ex-situ samples. For example, other oxidants,such as peroxides (e.g., hydrogen peroxide) and/or ozone may also beused in conjunction with oxygen, persulfate and/or phosphate, in someembodiments. In these and other embodiments, oligosaccharides (e.g.,cyclodextrin) may also be used to improve destruction rates. Examples ofsuitable oligosaccharides are described in U.S. Pat. No. 8,049,056 thatis herein incorporated by reference in its entirety. Destruction oraerosol formation rates may also be aided by raising the temperature ofthe reaction site. For instance, the temperature may be raised togreater than 50° C., greater than 70° C., or greater than 90° C.Destruction rates may also be aided by raising the pressure of thereaction site. For instance, the pressure may be raised to greater than1 atmosphere, greater than 2 atmospheres, or greater than 3 atmospheres.

In some embodiments, hydrogen peroxide may be introduced to generateheat and/or to increase the water temperature. If present, hydrogenperoxide may also increase bubble formation and bubble rise velocity tocontrol the rate of foam and/or aerosol formation relative to the rateof chemical oxidation of the PFAAs in the water. In some embodiments,hydrogen peroxide may be introduced at molar ratios within the range of1:10,000 to 1:100 of hydrogen peroxide to persulfate.

In various embodiments, reagents may be introduced into soil or groundwater using a well that may be vertically, horizontally or otherwiseoriented. Wells, if present, may be temporary, semi-permanent orpermanent. A well may include one or more conduits for transportingreagents from above-ground supplies to the target site, such as thesaturated layer or the smear layer. Conduits for different reagents maybe coaxial with each other or may run through distinct conduits in thewell. A second reagent may be introduced through a different well thanthe first and may deliver the reagent at a different depth than thefirst. However, the second well may be positioned so that the radius ofinfluence of the second compound substantially overlaps the radius ofinfluence of the first compound. For example, with vertically installedwells, the vertical axis of the second well may close to the verticalaxis of the first well. In some embodiments the two wells may be within20′, 15′, 10′, 5′ or 2′ of each other.

In embodiments where persulfate and phosphate are each used, thesecompounds may be used at approximately equal molar ratios or differentmolar ratios, such as for example the molar ratio of persulfate tophosphate may be 60:1, 30:1, 10:1, 5:1, 1:2 or 1:5. The molar ratio ofphosphate to oxygen, in embodiments where each compound is used, may beapproximately equal or may be different, such as for example the molarratio of phosphate to oxygen may be 600:1, 300:1, 100:1, 50:1, 10:1, 5:1or 3:1. In embodiments where persulfate and oxygen are used, thesecompounds may be present at approximately equal molar ratios or may bepresent at different molar ratios, such as for example the molar ratioof persulfate to oxygen may be 3000:1, 2000:1, 1000:1, 500:1, 100:1,50:1 or 10:1. In embodiments where hydrogen peroxide is used, the molarratio of persulfate to peroxide may be, for example, 1:1, 1:10, 1:5,1:2, 2:1, 5:1, 10:1, 50:1, 100:1 or 1000:1.

In embodiments where ozone is used in the solution, the molar ratio ofdissolved ozone to persulfate may be, for example, less than 1000:1,between 1000:1 and 10:1 or greater than 10:1. In these and otherembodiments, the gas bubble size may be less than one nanometer, lessthan 5 nanometers, less than 10 nanometers, less than 50 nanometers,less than 100 nanometers, less than 1 micron, less than 10 microns, orless than 50 microns. In these and other embodiments, the gas flow rateof the ozone-containing gas may be at least 0.05 cfh, at least .5 cfh,at least 5 cfh, or at least 10 cfh per liter liquid volume.

The reagents may be supplied at any effective concentration that may bedetermined, in part, from the type of soil, type of contaminant,concentration of contaminant, and the vehicle used to transport thereagent. In some embodiments, persulfate (i.e., S₂O₇) may be used at aconcentration of from 100 mg/L to 200 g/L; phosphate (i.e., PO₄) may beused at a concentration of from 100 mg/l to 20 g/l and soluble oxygenmay be used at a concentration range of from 0.1 mg/L to 200 mg/L. Insome select embodiments, ozone gas may be sparged in oxygen or air overa molar concentration range in the gas of about 1-20%. In these andother embodiments, hydrogen peroxide may be used at a concentration offrom 100 mg/l to 200 g/l.

The reagents used, for example oxygen, persulfate and/or phosphate maybe introduced to the target site simultaneously or sequentially. Whenintroduced sequentially, the time between sequential injections shouldnot be so great that the activity of the first-injected reagent has beensignificantly reduced before contacted with the second reagent. Reagentsmay be injected into different soil zones to provide for more completedestruction of contaminants.

With remediation systems that utilize sparging with either air or othergases in the saturated zone, there is the potential to volatilize themore volatile organics into the unsaturated zone before they can beoxidized. In addition, when adding oxidants to the saturated zone thatgenerate heat during reaction, volatile organics can be driven from thesaturated zone into the smear zone and/or unsaturated zone. The systemdescribed herein can trap and destroy those volatile organics.

In some embodiments, the saturated zone, smear zone, or unsaturated zonemay be pre-oxidized with an oxidant prior to applying an oxidant for thepurpose of destroying contaminants. This step may help to improve thecompleteness of chemical destruction in the later steps. The pH of anoxidant solution may be controlled to enhance, for example, stabilityand/or reactivity. In some embodiments a preferred pH range is 2.0-12.0.The pH of the solution may be controlled using a buffer, such as aphosphate. Once a target soil is chosen, an optimal pH for variousoxidant solutions can be determined in the field or lab by those ofskill in the art.

In addition to the desire to have longer lived reactive species topromote greater radial influence from the point of injection, there isalso a desire to reduce the number of injection events required toachieve cleanup standards. Typically, using known techniques, two ormore injection events are required to achieve the required reduction incontaminant concentration to meet the target clean-up goals. There areat least two reasons for this: 1) contaminants trapped in the “smearzone” are not targeted by existing ISCO technology, and 2) contaminantsand oxidants are slow to diffuse into and out of micro-pores within thesaturated zone, especially in fine grained soils. The system describedherein can address these issues as well as others.

In some embodiments, in-situ aquifer flushing is disclosed in whichwater containing cyclodextrin, or another cyclic oligosaccharide, isinjected to subsurface soil and/or groundwater to enhance PFAS removalfrom the soil and groundwater as it passes through the soil matrix to ahydraulically downgradient groundwater extraction well where groundwatercontaining a cyclodextrin-PFAS complex is extracted and removed usingthe described gas infusion technology or by other suitable methods. Insome embodiments, the cyclic oligosaccharide is a beta-cyclodextrin oranother derivative, such as hydroxyl-propyl beta cyclodextrin. Thecyclodextrin or other type of oligosaccharide may be added to water inconcentrations ranging from 0.001% to 10% when used in aquifer flushingto capture and remove PFAS from the subsurface. While not wishing to bebound by theory, it is believed that in some cases, the cyclicoligosaccharide may encapsulate or otherwise associate with the PFAScompounds in the soil and/or groundwater, thereby facilitating removal.

Poly and Perfluorinated Alkyl Substances (PFAS)

Poly and perfluorinated alkyl substances (PFAS) here is defined as anyand or all of the fluorinated organic compounds being considered forregulation by the US Environmental Protection Agency in environmentalmedia of soil, sediment, and water. PFAS is categorized as non-polymerand polymer compounds. The non-polymer compounds include poly and perfluorinated organic compounds and the polymer compounds includefluoropolymers and fluorotelemers. In addition, precursor fluorinatedand non-fluorinated compounds have been identified that may result inthe formation of toxic fluorinated compounds. There may be greater than3,000 fluorinated organic compounds released to the environment

We have identified the need to remove PFAS compounds from soil andgroundwater without the concern for creating other toxic organiccompounds either fluorinated or non-fluorinated. Any form of in situ orex situ chemical oxidation has the potential to form incomplete reactionproducts or by-products when reacting with the PFAS before completemineralization to fluoride anion can occur. These compounds must beremoved from the soil and groundwater or destroyed completely in situ.

In one embodiment, soil and groundwater may be contacted withcyclodextrin or its derivatives to remove PFAS from the ground or groundwater before any degradation or destruction method is employed. Onceseparated from the environmental media, then the PFAS may be destroyed.Cyclodextrin in effect can act as a “concentration and removal stepprior to destruction” for the typically low concentration of PFASpresent in the environment in low parts per billion. One example may beproviding in situ treatment of soil and groundwater by flushing withcyclodextrin and or its derivatives through the soil to remove the PFASfrom the soil forming a cyclodextrin-PFAS complex and then extractingthe cyclodextrin-PFAS complex for ex situ treatment by any of themethods described here or described in the attached documents.

Treatment with ozone gas may result in some portion of the PFAS insolution being transferred to the off-gas where it may be captured in atrap(s) and subsequently destroyed in the trap or returned to thereactor for further treatment. In some other embodiments additionalenergy input to the water to be treated using one or more of ozone,peroxide, and persulfate may be provided. The required activation energyand radical production needed to degrade or destroy the PFAS may beincreased by these methods and other methods of homogeneous and/orheterogeneous catalysis. The ideal method of catalysis would act as acatalyst for one or more of the oxidants of ozone, peroxide, orpersulfate.

It may be desirable to destroy PFAS in the presence of cyclodextrin andcomplexed with cyclodextrin. Another advantage of using one or more ofthe enhancements identified herein can be that a lower concentration ofchemical necessary for PFAS degradation and destruction may be used.

Catalysis of Persulfate

Homogeneous catalysis of persulfate may involve heat, ultraviolet light,ultrasound and chemical activation by metals, bi-metals or organiccompounds such as cyclodextrin. Heterogeneous catalysis may involveactivation by metals based on cobalt, iron, and manganese. Heat,alkaline, and metals may be used. It is believed that cyclodextrin alonemay act as an activator of persulfate under certain pH conditions.Peroxides may also be used to activate persulfate. Ozone may be used toactivate persulfate.

Catalysis of Ozone

The main methods of homogeneous ozone catalysis are by alkalineconditions, ultraviolet light, ultrasound, and high pressure.Heterogeneous catalysis by metals such as manganese-based may be used.Peroxides may also be used to activate ozone. Peroxides have been usedto coat ozone nanobubbles providing for a higher activation energy.Persulfates may act to enhance ozone nanobubble reactivity.

Cavitation Enhanced Treatment

In some embodiments, chemical processes can be combined with cavitation,which may be induced, for example, by hydrodynamics or by ultrasound.Hydrodynamic cavitation is a process which involves vaporization, bubblegeneration, and bubble implosion in a flowing liquid with a decrease andsubsequent increase in local pressure. Cavitation occurs when localpressure drops below the saturated vapor pressure of the liquid andsubsequently returns to above the vapor pressure. If the recoverypressure is lower than the saturated vapor pressure then flashvaporization occurs. In water pipes, hydrodynamic cavitation generallyoccurs either due to an increase in kinetic energy (through an areaconstriction) or due to an increase in the pipe elevation. Hydrodynamiccavitation may be created, for example, by allowing a liquid to passthrough an orifice at a certain flow rate or by a mechanical rotationcreating a vortex in a liquid. In case of an orifice, the combinedeffects of pressure and kinetic energy create the hydrodynamiccavitation generating high energy cavitation bubbles.

It is believed that hydrodynamic cavitation can contribute to organiccompound destruction in a number of ways and/or enhanced PFAS containingaerosol and foam formation. These mechanisms may include, for example,localized high temperature, higher surface area, increased mixing,formation of radicals and mass transfer from a liquid to a foam oraerosol. As a result, reactions that would normally require hightemperature and/or pressure can be successfully completed. Cavitationbubble generation and their subsequent growth and collapse produce veryhigh energy densities, high local temperatures and high pressures at thesurface of the bubbles for a short time. While uncontrolled cavitationcan be damaging, controlled cavitation can be used to enhance chemicalreactions. For example, controlled cavitation can be used to propagatecertain difficult reactions which are otherwise kinetically orthermodynamically unfeasible under normal conditions. These reactionscan be at least partially facilitated by free radicals generated duringthe cavitation process as a result of, for example, the dissociation ofthe trapped vapors in cavitation bubbles. In some cases, this may resultin an increase in the rate of hydrolysis of recalcitrant organicpollutants, resulting in improved treatment efficiency.

Different cavitation devices can be used for generating different sizedcavitation bubbles. Some hydrodynamic cavitation devices can be tuned togenerate picobubbles (less than 1 nm), nanobubbles (less than 1 μm), andmicrobubbles (less than 1 mm) under certain conditions of velocity andpressure. Picobubbles have larger surface area per unit volume ascompared to nanobubbles, and nanobubbles have larger surface area perunit volume compared to microbubbles. Bubble size can be measured usinglaser diffraction equipment.

Different chemical reagents including oxidizing and reducing agents canalso be used with hydrodynamic cavitation processes. The oxidizingagents may include oxygen (O₂), ozone (O₃), hydrogen peroxide (H₂O₂),inorganic peroxides, persulfate, permanganate, and percarbonate. Theymay be added simultaneously or sequentially, in any order.

Suitable reducing agents may include, but are not limited to,cyclodextrin, hydrogen, iron, zero valent iron, ferrous sulfate, sulfurdioxide, hydrogen sulfide, dithionate including sodium dithionate,thiosulfate, iodionites, hydrogen peroxide, oxalic acid, formic acid,ascorbic acid, Vitamin B12, reducing sugars, sulfites, phosphites, andhypophosphites.

The chemical reagents can be introduced to the cavitation devices inmany forms including solid, liquid, gas or their combinations togenerate cavitation bubbles of varied sizes. In one embodiment, oxygenalone or oxygen and ozone or oxygen and ozone and peroxide can bepre-dissolved in a persulfate solution prior to introducing them into ahydrodynamic cavitation device to generate picobubbles, nanobubbles,and/or microbubbles. These bubbles, once formed, can then collapse orremain stable in solution depending on the flow velocity, pressure drop,and ionic strength of the solution.

Hydrodynamic cavitation can be achieved in various ways including theuse of specific devices designed for producing localized hydrodynamiccavitation. Such devices include, for example, the CavTube® hydrodynamiccavitation device available from Eriez Flotation. In one set ofembodiments, oxygen can be dissolved in persulfate solution and passedthrough a hydrodynamic cavitation device. In a specific embodiment, thedevice is operated at a flow rate of 1.5 gallons per minute (gpm) thatmay result in a pressure drop of 25 pounds per square inch (psi) and mayform bubbles of varying sizes ranging from picobubbles (less than 1 nm)to microbubbles (less than 1 mm). In various embodiments, liquid orslurry at flow rates ranging from 0-0.5, 0.5-2.0, 2.0-5.0, 5.0-10.0,10.0-100.0, and 100-1,000 gpm may be used with pressure drops of 0-20,20-30, 30-40, and 40-100 psi. The concentration of the persulfatesolution can be 0-1 mg/l, 1-100 mg/l, 100 mg/l-1 g/l, and 1 g/l-100 g/l.Oxygen or oxygen/ozone in the persulfate solution may be 0-1 volumepercent, 1- 10 volume percent, or 10- 40 volume percent. The pH of thesolution may be, for example, about 3.0 to about 11.0, about 5.0 toabout 10.0 or about 6.0 to 9.0. In some other embodiments, buffers ofvarious pH ranges such as 1-3, 3-5, 5-7, 7-9, and 9-11 can be used.Alkali metal hydroxide or alkali metal salts or both can be used toprepare buffers of a specific pH.

In some embodiments, hydrodynamic cavitation can be used at varioustemperatures to tailor the destruction to different contaminants anddifferent rates of destruction. In one particular embodiment, thesolution temperature can be from about 4° C. to about 90° C.

Hydrodynamic cavitation devices can also be incorporated in differentreactor designs for ex-situ treatment of water contaminants includingPFAS. The reactor designs may vary depending on whether transfer to anaerosol or a foam is desirable. In one embodiment, a single gas infusionreactor can include multiple compartments wherein each of thecompartments can include a recycle option. In another embodiment, amulti-stage reactor vessel can be used with or without a recyclingoption for each vessel as shown in FIG. 5. FIG. 5 illustrates an ex-situtreatment process in which extracted groundwater or slurry is treatedabove the ground. In some embodiments, multiple reactor vessels can beconnected in series, such that liquid flows from one reactioncompartment to the next once a certain volume of fluid accumulates in areaction compartment. In some other embodiments, liquid transfers fromone reaction compartment to the next reaction compartment can be throughpumps connected in series after each compartment. In embodiments thatinvolve feeding a slurry, clean soil may be removed first at the soilpre-treatment phase before the water contaminated with contaminantsincluding PFAS enters the water treatment phase as shown in FIG. 5.

Ex-situ treatment of the extracted slurry or groundwater may include, insome embodiments, treatment with one or more of the following chemicalreagents: persulfate, oxygen, ozone, (hydrogen peroxide), andcyclodextrin. In some other embodiments, one or more of these chemicalreagents may be recirculated in each reaction compartment through pumpsconnected in series at the bottom of each compartment.

In some embodiments, the hydrodynamic cavitation devices can be insertedeither on the inlet to the reactor or in-line on the recycle line orinside the compartments or at any combination of the three locations toenhance the reaction with PFAS. In some cases, multiple cavitationdevices can be used and may be placed in parallel or in series with eachother. Oxygen or oxygen/ozone gas may be added to or passed through thecontaminated water upstream of the hydrodynamic cavitation device/s toincrease the amount of cavitation bubbles. In some or all the aboveembodiments, the headspace above the liquid in each vessel can betreated in-place and/or removed from the reactor for separate treatment.

When transfer to an aerosol or foam is not used as part of thecontaminant removal and destruction process, a plug flow reactor designbased on a tubular or a channel design may be used to degrade and/ordestroy PFAS without significant transfer from the liquid phase toaerosol or foam above the liquid level. A recycle line may be used withthe plug flow reactor to recycle a portion of the treated flow. Thecavitation device can be inserted in-line with the plug flow reactor andthe oxygen or oxygen/ozone may be added ahead of the cavitation deviceas previously described. In-line static mixers may also be added to theplug flow reactor. In a plug flow reactor, a hydrodynamic cavitationdevice can be inserted directly into the plug flow reactor or in therecycle line, and oxygen or oxygen/ozone gas may be added to thecontaminated water prior to the device to increase the amount ofcavitation bubbles. In a gas infusion reactor, hydrodynamic cavitationdevices are inserted either into the inlet pipe to one or more reactorsor into the recycle line of one or more reactors. Warm or heated air orother gas may also be added to the liquid prior to passing the liquidthrough the hydrodynamic cavitation devices to add heat to the systemand to enhance the rate of degradation of PFAS. Some or all the aboveembodiments of reactors may also include an in-line static mixer aheadof the cavitation devices.

In some embodiments, aerosol and/or foam is collected in a water trapwhere it is concentrated into a smaller volume of water which may beavailable as or converted into an alkaline solution by the addition ofbuffer or alkali metal hydroxide, and which is subsequently ozonated ina process called alkaline ozonation as shown in FIG. 5. Theconcentration of PFAS may include a volume reduction of more than 10×,more than 20×, more than 50×, more than 100×, more than 1000×, or morethan 10,000×.

In some embodiments, oligosaccharides such as cyclodextrin can be usedto extract, isolate and/or destroy PFAS from the environmental media.Examples described herein are directed to cyclodextrin but it will beunderstood that other oligosaccharides may be just as applicable.Oligosaccharides such as cyclodextrin can enhance foaming as well asaerosol formation of the contaminated water. Therefore, cyclodextrin,for example, can be used in transferring poly fluoroalkyl compounds toeither a foam layer or to an aerosol form for subsequent removal anddestruction of contaminant. For example, in the case of PFAS, thecontaminant may be transferred to a foam layer or to an aerosol in theform of cyclodextrin-PFAS complexes. Hydrodynamic cavitation can also becombined to further enhance transfer of PFAS and cyclodextrin-PFAS fromthe contaminated water to the foam layer or aerosol form. Thehydrodynamic cavitation can therefore provide a reactive environment andcan also produce bubbles that lead to the formation of aerosols, foamsor both.

Cyclodextrin can be applied to both ex-situ and in-situ removal anddestruction of PFAS. In an in-situ process, cyclodextrin solution may beinjected to the subsurface soil and/or groundwater that is contaminatedwith PFAS to form cyclodextrin-PFAS complexes. The cyclodextrin-PFAScomplexes can be further treated in-situ for their destruction ordegradation. Further treatment may include the techniques describedherein including injecting one or more of oxygen, ozone, and persulfatesolution into the subsurface soil and groundwater. An ex-situ processmay include injecting cyclodextrin solution into the subsurface soiland/or groundwater contaminated with PFAS, extracting the water orenvironmental media comprising PFAS and cyclodextrin-PFAS, and treatingthe extracted water or media for the removal and/or destruction of PFAS.The clean water or the water from which PFAS has been removed can beinjected back to the groundwater.

In some embodiments, PFAS removal using cyclodextrin can be enhanced bysubjecting the extracted water to bubbles, which may include nanobubblesand picobubbles. These bubbles can be generated by various methodsincluding, but not limited to, sparging a gas through the water, warmingthe water, or by hydrodynamic cavitation as described earlier. When thecyclodextrin, PFAS or the cyclodextrin-PFAS complexes pass throughcavitation devices and react with cavitation bubbles, their transferfrom water to foam or aerosol and/or their destruction may be enhanced.In some embodiments, a gas including oxygen, ozone, or air may be passedthrough the environmental media or water contaminated with PFAS beforeallowing the liquid to pass through the cavitation devices to increasethe potential for bubble formation and thus further enhance thecyclodextrin-mediated transfer and destruction of PFAS.

In some other embodiments, the environmental media or water contaminatedwith PFAS may be pre-treated with oxidants or reductants before passingthe liquid through the cavitation devices to further enhance thecyclodextrin-mediated transfer and destruction of PFAS. In someembodiments, both an oxidant and a reductant can be combined to furtherenhance the cyclodextrin-mediated transfer and destruction of PFAS. Forexample, oxidizing agents disclosed herein, including oxygen, ozone,air, persulfate and/or peroxide can be provided in combination with, orsequentially with, a reducing agent that may include, but are notlimited to, such as cyclodextrin, hydrogen, iron, zero valent iron,ferrous sulfate, sulfur dioxide, hydrogen sulfide, dithionate includingsodium dithionate, thiosulfate, hydrogen peroxide, oxalic acid, formicacid, ascorbic acid, Vitamin B12, reducing sugars, sulfites, phosphites,and hypophosphites.

In some embodiments, cyclodextrins may also be combined with surfactantsto further enhance removal of PFAS from soil or from water when alone orpresent with co-contaminants including non-aqueous phase liquids(NAPLs). Cyclodextrin in combination with sugar-based surfactants orbiosurfactants may be used for treatment of environmental mediaincluding contaminants on surfaces or sorbed to soil, sediment, rock, orin water. Surfactants may also enhance removal of the non-complexed orcomplexed cyclodextrin-PFAS in the environmental media or water byenhancing foam or aerosol formation for subsequent removal anddestruction. Cyclodextrin molecules may be contained within thesurfactant micelle or outside of it.

In some embodiments, salt anions including sulfates and phosphates mayenhance the inclusion of PFAS and other hydrophobic molecules into thecyclodextrin cavity by a phenomenon called “salting-out”. The sulfatesresulting from reacted persulfate and phosphates from phosphate buffercan enhance the attraction of hydrophobic molecules, such as ozone, orhydrophobic inorganic or organic contaminants to the cyclodextrincavity. Anions such as perchlorate or bromate may react with aninorganic or organic cation to form a hydrophobic molecule that may beattracted to the cavity. Cyclodextrin-PFAS complex can then betransferred from the treated water for removal and/or destruction.

Contaminants can be transferred to a foam directly or via a complex witha polysaccharide such as cyclodextrin. In some cases, more than 10%,more than 20%, more than 50% or more than 75% of organic contaminants(eg, PFAS) can be transferred from the ground water or soil to the foam.The foam can be removed from the top of the aqueous phase using, forexample, a weir, a knife or a vacuum system. Once the foam is isolated,the contaminants therein can be contained or destroyed. This can help toconcentrate the contaminants in a smaller volume where they can be moreefficiently stored or destroyed using, for instance, the processesdescribed herein or other processes such as thermal or electrochemicaltechniques. After foam has been removed from the aqueous phase, theaqueous phase can be reintroduced to the system to withdraw additionalcontaminants from the water or soil. In some cases, additional reagentsincluding oxidants, reductants or polysaccharides can be added at thisstage.

Ultrasound or Ultraviolet Light

High energy treatments such as ultrasound, electrochemical treatment andultraviolet light can be used to destroy or partially destroy PFAS. Thehigh energy techniques may be used in place of or in addition to thechemical oxidation methods described herein. The high energy techniquesmay occur upstream or downstream of the oxidation, or may take place atthe same time. The extracted groundwater containing cyclodextrin,cyclodextrin-PFAS complex, unassociated PFAS, and potentially otherco-contaminants, may be treated by chemical oxidation and that may beenhanced by addition of either ultrasound or ultraviolet light. It isknown that ultrasound in combination with ozone can induce cavitation ofthe ozone and oxygen gas bubbles in solution yielding an energy releaseto the solution. When ultrasound is used the physical method ofapplication and configuration, energy per volume applied, frequency,solution pH, and treatment time may be considered. When ultraviolet isused the physical method of application and configuration, energy pervolume applied, wavelength, solution pH, and treatment time may beconsidered. Ultrasound can be used with ozone and persulfateindividually, or ozone, peroxide, and persulfate or ozone and persulfatecan be used in combination. Ultraviolet light can be used with ozone,(ozone-peroxide combined), and persulfate, individually but not withozone, peroxide, persulfate or ozone and persulfate in combination.Either ultrasound or ultraviolet light may also be used alone withoutchemical oxidants and/or reductants as a pre-treatment step fordegradation of the cyclodextrin or cyclodextrin-PFAS complex prior tochemical oxidation with any one or more of ozone, peroxide, persulfate.

Trap Off-Gas Return

It has been reported that PFAS in the off-gas from treatment with ozone,oxygen, or air can be captured in a trap containing water or alkalinesolution of tribasic phosphate and/or hydroxide. In some embodiments,the off-gas after leaving the trap or traps can then be returned to thenext stage in the treatment reactor for further treatment of anyresidual PFAS in the off-gas. The returned off-gas may be added at theinlet to the reactor, in a recirculation line to a reactor, or to theozone gas supply line leading to the reactor. This may eliminate anypotential discharge of PFAS in the off-gas to the ambient environmentmaking for a closed system.

Secondary Treatment of Extracted Groundwater by Electrochemical Reactor

A second ex-situ treatment step of extracted groundwater or any waterthat may be used after the initial treatment described here could be anelectrochemical reactor for additional oxidation and/or reduction so asto further degrade or destroy any residual cyclodextrin-PFAS complex andPFAS. Electrochemical reactors can be used to degrade PFAS, PFOA andPFOS under different conditions of electrode type, energy input pervolume, and treatment time. The degree of PFAS treatment byelectrochemistry can be highly dependent on the specific electrodes usedin the reactor and the operating conditions of the reactor. In additionto further destruction of any residual PFAS from leaving the initialtreatment step, the added advantage of using a second treatment stepwith electrochemical reactor may be that any potential perchlorate orbromate formed by the use of ozonation of free chloride and bromide inthe water can be reduced at the cathode in the electrochemical reactorbefore discharge or reuse of the treated water. The treated water can bereused for chemical make-up water and reinjected into the ground.

Other traditional methods of secondary treatment in place ofelectrochemical treatment may include removal, concentration orsequestration techniques such as the use of granular or powderedactivated carbon, ion exchange resin and nanofiltration. These may beused after chemical oxidation or after high energy treatments.

EXAMPLES

Various experiments were performed to support the concepts discussedhere. The experimental procedures and results are presented in thissection. PFAS concentrations were analyzed by modified EPA Method 537.Fluoride concentration was analyzed by EPA Method 340.2 that uses a lowlevel selective ion electrode.

Example 1

In this example, the experiment had three sequential phases where thedegradation of PFAS (i.e. PFOS and PFOA) was evaluated. The experimentwas performed in a plastic column reactor with a sparger at the bottomusing steam distilled water only containing 3 ug/l fluoride as abackground concentration. In Phase I, PFAS degradation was measuredusing oxygenated distilled water. In Phase II, oxygenated persulfate wasused, and in Phase III oxygenated buffered persulfate (OBP) with asolution pH of approximately pH 9 was used.

Procedure

A plastic reactor having a volume of approximately 4 liters andapproximate dimensions of 16 inches height and 12 inches width wasthoroughly cleaned and filled with the steam distilled water and spikedwith 200 micrograms (ug)/liter of PFOS. Prior to testing, fluoridesorption to the plastic reactor was evaluated by analyzing a PFAS andfluoride spiked solution in the reactor during 2.5 hours of stirring.The results showed that approximately 750 ug/liter concentration offluoride in tap water was constant over 2.5 hours. Leaching or sorptionof fluoride to the plastic reactor was not detected as the fluorideconcentration remained constant.

During Phase I of the experiment, the potential for volatilization orsorption of PFAS to or from the reactor was evaluated by collecting andanalyzing samples for PFAS and fluoride analysis after 60 minutes ofsparging pure oxygen into the reactor at 10 SCFH (standard cubic feetper hour).

During Phase II of the experiment, oxygenated persulfate was evaluatedby adding 60 grams per liter persulfate to the reactor and sparging pureoxygen at 10 SCFH. After 1 hour of sparging, the oxygen introduction wasterminated and samples were collected and analyzed. Thereafter, sodiumhydrogen phosphate buffer was added and mixed with a magnetic stirreruntil dissolved to yield a concentration of 8.6 grams /liter.

During Phase III, oxygenated buffered persulfate was tested. Whilesparging the fluid in the reactor with oxygen at approximately 10 SCFH,samples were collect at t=10 minutes, t=30 minutes and t=60 minutes. Att=60 minutes, the oxygen supply was terminated and the solution wascontinuously stirred until t=90 minutes, when a sample was collected.

Experimental results are shown in Tables 1.1 and 1.2 provided below.

TABLE 1.1 Fluoride concentration in tap water in the plastic reactorover time TAP 10 30 60 150 Units WATER min min min min Fluoride (F) mg/L0.74 0.74 0.75 0.76 0.74

TABLE 1.2 PFOS and PFOA Concentrations during the Phases of SequentialTesting Phase I- Spiked, Phase II - oxygenated oxygenated distilledwater persulfate Spike Initial After After After Initial After % conc.Conc. 1 hr. 2 hrs. 17 hrs. conc. 1 hour removal PFOA 200 225 220 220 220220 180 18% PFOS 200 205 210 220 180 180 43 76% Phase III Oxygenatedbuffered persulfate Initial After After After After % conc. 10 min 30min 60 min 90 min removal PFOA 180 120 73 51 37 79% PFOS 43 29 17 13 1467%

As shown in Table 1.2, there was no appreciable change in PFOS or PFOAconcentration observed during Phase I testing with oxygenated distilledwater. Accordingly, spiked PFOS and PFOA were not observed to sorb orvolatilize to or from the plastic reactor. However, some decrease wasobserved in both PFOS and PFOA during Phase II testing using oxygenatedpersulfate. A greater decrease was observed in Phase III testing usingoxygenated buffered persulfate. As such, oxygenated persulfate alone isshown to facilitate removal or destruction of PFAS.

The following conclusions are drawn from the experimental results:

-   -   PFOS and PFOA did not significantly sorb to or volatilize from        the plastic reactor.    -   Fluoride concentration was conserved in the plastic reactor.    -   PFOS and PFOA were removed from solution by oxygenated        persulfate, and oxygenated buffered persulfate

Example 2

In this example, testing was performed in a taller plastic columnreactor than in example 1. The reactor had a sparger at the bottom andused steam distilled water that was spiked with PFAS (i.e. PFOS andPFOA) and then treated with sparged ozone (6%) and oxygen (94%), andbuffered persulfate with a solution pH of approximately pH 9.0.

Procedure

The plastic column reactor used in this test was 5 feet in length withan inner diameter of 2.75 inches. The reactor was thoroughly cleaned,filled with 2.7 liters of the steam distilled water, and then spikedwith PFOS and PFOA each at 500 ug/liter.

Fluoride concentrations were measured in the distilled water before andafter PFAS spiking, after 1 hour of oxygenation to mix the spikingsolution, after buffered persulfate was added at the same concentrationsas in Example 1, and at various intervals during sparging with ozone andoxygen. Based on the amount of PFAS measured prior to sparging withozone, the theoretical organofluorine contained in the PFAS was 590ug/l.

The fate of PFAS and fluoride in the reactor was evaluated by collectingand analyzing samples for PFAS and fluoride analysis during 9 hours ofsparging ozone and oxygen into the buffered persulfate within thereactor at 5 SCFH (standard cubic feet per hour). The experimentalresults are shown in FIG. 2.

Only a small amount of background fluoride concentration was detected inthe distilled water at 3 ug/l, the PFOS and PFOA spikes at 4 ug/l, andbuffered persulfate at 3 ug/l. However, fluoride concentrations slowlyincreased during ozonation as PFOS and PFOA were degraded to fluorideion until, after 9 hours of ozonation, 86% of the fluoride contained inthe PFAS had been broken down and released. After 1 hour of bufferedpersulfate solution ozonation, 90% of the PFOS and PFOA had beenremoved. After 9 hours, this removal rate had increased to 99.9%.

The following conclusions were drawn:

-   -   Fluoride did not sorb or leach to or from the plastic column        reactor.    -   PFOS and PFOA did not sorb to the plastic column reactor.    -   86% de-fluorination of known PFAS occurred within the 9 hours of        testing.    -   99.9% PFOS and PFOA were removed during sparging buffered        persulfate with ozone (6%) and oxygen (94%)

Example 3

In this example, a sample of groundwater collected from an actual sitewhere AFFF was released to the subsurface containing 167 ug/l of knownPFAS compounds was tested initially using oxygenated buffered persulfateand then ozonated buffered persulfate testing over a 10.5 hour period.The 167 ug/l of PFAS in the groundwater consisted of 13 individual PFAScompounds with the majority as PFOS at 120 ug/l. The theoreticalorganofluorine concentration in the total PFAS was 110 ug/l.

Procedure

The plastic column reactor with a sparger at the bottom was thoroughlycleaned before a liter of steam distilled water containing approximately3 ug/l fluoride was added to the reactor. After being in the reactorovernight, the distilled water in the reactor was tested and found tocontain approximately 4 ug l fluoride background concentration.

Then, 2.6 liters of the AFFF contaminated groundwater then was pouredinto the plastic column reactor and sampled for fluoride before spargingoxygen into the reactor contents at 5 CFH to check for stabilization offluoride. An off-gas water trap was fitted to the reactor for thecollection of any PFAS or fluoride in the off-gas during testing forsubsequent analyses. The trap was filled with 200 ml of distilled water.Persulfate and phosphate buffer were added to the reactor contents toproduce the same concentrations as in the previous experiments with asolution pH of approximately pH 9.0. Oxygen was sparged at 5 SCFH for 1hour but at this flowrate, foam formed and rose up the column and intothe exhaust trap. Therefore, the flowrate was reduced to 0.5-1 SCFH tominimize foaming.

After this hour of testing with oxygenated buffered persulfate, thereactor contents were ozonated by sparging ozone (6%) and oxygen (94%)into the reactor at a flowrate of 1-5 SCFH for a period of 9.5 hours.During the entire 10.5 hour testing period, samples were periodicallycollected and analyzed for fluoride and PFAS. Also, the contents of theoff-gas water trap was periodically collected for analysis and refilledwith fresh distilled water.

During the one hour of oxygenated buffered persulfate testing, sampleswere not analyzed for PFAS. However, during the subsequent 9.5 hours,samples were analyzed and most PFAS decreased significantly and PFOS(the predominant contaminant) decreased 99% while the sum of all PFAScompounds decreased 70%. The experimental results for example #3 arepresented in Table 3 below.

PFAS was also detected in the off-gas water trap indicating that PFASwas transferred from the liquid phase via aerosols and/or foam to thetrap. Not all the consecutive off-gas water traps were analyzed for PFASso the total amount of PFAS transferred is not known. However, the twotraps that were analyzed (2 to 3.5 hrs. and 3.5 to 5.5 hours)demonstrated that at least 37 ug of PFAS, which was mostly as PFOS, wastransferred. This is approximately 4% of the PFAS that was in thereactor at time zero.

During the one hour of oxygenated buffered persulfate, fluorideconcentrations in the reactor did not increase, in fact, they decreasedvia transfer of fluoride to the off-gas trap. However, once ozonationbegan, fluoride concentrations in the reactor began to increase rapidlyfrom approximately 13 ug/l to 831 ug/l after 9.5 hours of ozonation.

Significant amounts of fluoride (96 ug) were transferred via aerosolsand/or foam to the exhaust water trap during the hour of bufferedpersulfate oxygenation. So much fluoride was transferred to the exhaustwater trap that the fluoride concentration in reactor actuallydecreased. Smaller amounts of fluoride (15 ug) continued to betransferred from the reactor to the exhaust during the 9.5 hours ofozonation, presumably via aerosols since foaming was not observedentering the exhaust water trap during the ozonation phase.

TABLE 3 PFAS Treatment results for Example #3 Treatment Time ParametersUnits t = 0 2 hours 3.5 hrs. 5.5 hrs. 7.5 hrs. 10.5 hrs. PFAS notTreated below Detection Limits in Reactor Perfluorobutane Sulfonate(PFBS) ug/L 0.38 3.0 3.1 3.3 2.9 2.4 Perfluoroheptane sulfonate ug/L 2.31.8 1.2 0.61 1.1 0.45 Perfluoroheptanoic Acid (PFHpA) ug/L 0.47 4.4 8.511 14 6.2 Perfluorohexane Sulfonate (PFHxS) ug/L 13 24 26 18 18 5.0Perfluorohexanoic Acid (PFHxA) ug/L 2.3 26 30 32 32 25Perfluoro-n-Octanoic Acid (PFOA) ug/L 2.1 5.9 6.1 4.2 4.7 1.6Perfluorononanoic Acid (PFNA) ug/L 0.79 0.62 0.62 0.34 1.0 0.21Perfluorooctane Sulfonate (PFOS) ug/L 120 40 26 6.5 16 1.8Perfluoropentanoic Acid (PFPeA) ug/L 1.3 4.8 5.8 6.1 6.4 7.1 PFAStreated to below Detection Limit levels in Reactor PerfluorodecaneSulfonate ug/L 0.24 <0.22 <0.22 <0.22 <0.22 <0.22 Perfluorodecanoic Acid(PFDA) ug/L 0.22 <0.20 <0.20 <0.20 <0.20 <0.20 6:2 Fluorotelomersulfonate ug/L 16.5 20 8.5 0.67 <0.21 <0.21 8:2 Fluorotelomer sulfonateug/L 5.3 0.92 <0.28 <0.28 <0.28 <0.28 Perfluorobutanoic acid ug/L 0.40<200 <200 <200 <200 <200 Perfluoroundecanoic Acid (PFUnA) ug/L 2.5 0.185<0.14 <0.14 0.17 <0.14 Sum of detected PFAS (concentration) ug/l 168 132116 83 96 50 Total concentration decrease in Reactor % — 22% 31% 51% 43%70%

In total, the 2,050 ug of fluoride that was released from the PFAS asmeasured in the reactor (1,939) or traps (111 ug) were approximatelyseven times the amount of organofluorine contained in the known mass ofPFAS (107 ug) at time zero. This indicates that there were otherorganofluorine compounds in the groundwater sample that were not beinganalyzed by the current PFAS analytical method of EPA Method 537. Thisis consistent with the literature showing that AFFF is known to containmany dozens of fluorinated compounds that are not yet able to beanalyzed because no standards exist. Therefore, much of thisunidentified PFAS must have been de-fluorinated by both the oxygenatedand ozonated buffered persulfate.

The following conclusions are drawn from the experiment results:

-   -   Both oxygenated and ozonated buffered persulfate remove PFAS        from the reactor by both chemical destruction/defluorination and        physical transfer as an aerosol and/or foam to the off-gas water        trap.    -   Overall removal of identifiable PFAS after a total of 10.5 hours        of oxygenated and ozonated buffered persulfate treatment was        70%.    -   The large amount of fluoride released during the test indicated        that there was a large amount of other PFAS compounds in the        AFFF contaminated groundwater than those detected.

Example 4

In another example, groundwater contaminated with AFFF contained 380ug/l of known PFAS compounds underwent both oxygenated bufferedpersulfate and ozonated buffered persulfate testing over a 19 hourperiod. Fifteen individual PFAS, primarily PFOS at 320 ug/l, weredetected in the sample.

The same plastic column reactor used in example 3 was re-used afterthoroughly cleaning and testing that the column neither sorbed norleached fluoride. Sodium persulfate and phosphate buffer were dissolvedinto 5 liters of the contaminated groundwater at the same concentrationsas in previous experiments.

Oxygen was sparged into the bottom of the reactor with a diffuser at aflowrate varying from 2 to 5 CFH for 2 hours with the exhaust passingthrough the off-gas water trap whose contents were collected andreplaced periodically with new distilled water. After this phase, ozoneand oxygen were sparged for 17 more hours. Samples from the reactor andof the trap contents were periodically measured for fluoride and PFAS.

Table 4 below presents the concentration of the measured PFAS in thereactor during the 19 hours of treatment with a mixture of oxygen,ozone, and buffered persulfate. The concentration of the sixteendetected PFAS in the groundwater decreased significantly in the twohours of oxygenated buffered persulfate, from 90-99+% depending on thespecific compound, averaging 99% overall. The majority of this PFASreduction was due to transfer from the reactor to the off-gas trap asaerosols or foam, considering that the total amount of fluoride in thesystem (i.e. contained in the reactor plus trap) did not change.

TABLE 4 PFAS Treatment Results for Example #4 Treatment TimeParameters/Sample Name UNITS Start 2 hours 5 hours 8 hours 11 hours 19hours PFAS not Treated below Detection Limits in Reactor PerfluorobutaneSulfonate (PFBS) ug/L 0.29 0.0048 2.2 2.0 1.5 2.8 Perfluoroheptanesulfonate ug/L 5.4 0.027 0.073 0.018 <0.009 0.32 Perfluoroheptanoic Acid(PFHpA) ug/L 0.40 <0.012 1.3 0.93 0.074 8.1 Perfluorohexane Sulfonate(PFHxS) ug/L 17 0.081 3.9 1.6 0.052 13 Perfluorohexanoic Acid (PFHxA)ug/L 1.7 0.017 5.3 5.2 2.8 17.0 Perfluoroctanoic Acid (PFOA) ug/L 2.80.023 0.12 0.053 0.013 0.50 Perfluorooctane Sulfonate (PFOS) ug/L 3203.0 0.68 0.16 0.071 3.2 Perfluoropentanoic Acid (PFPeA) ug/L 0.76 0.0731.8 2.5 2.5 3.6 PFAS treated to below Detection Limits in ReactorPerfluorodecane Sulfonate ug/L 0.53 0.011 <0.011 <0.011 <0.011 <0.22Perfluorodecanoic Acid (PFDA) ug/L 0.45 <0.017 <0.017 <0.017 <0.017<0.20 6:2 Fluorotelomer sulfonate ug/L 12 0.090 0.53 0.044 <0.016 <0.218:2 Fluorotelomer sulfonate ug/L 12 0.16 0.039 0.014 <0.014 <0.28Perfluorobutanoic acid ug/L 0.30 0.0066 <0.007 <0.007 <0.007 <2.0Perfluorononanoic Acid (PFNA) ug/L 0.75 0.017 0.039 0.026 0.014 <0.19Perfluoroundecanoic Acid (PFUnA) ug/L 5.6 0.066 0.025 0.023 <0.009 <0.14Sum of detected PFAS (concentration) ug/l 380 3.6 16 13 7.0 49 Totalconcentration decrease in Reactor % — 99.1% 95.8% 96.7% 98.2% 87.2%

During the full 19 hours of testing, seven of the individual PFAScontinued to decrease in concentration to below detection limits,reaching a 99.8% removal rate. During the ozonation phase, especiallybetween hours nine and sixteen, 8 individual PFAS compounds increased inconcentration (such that the overall reduction in PFAS concentration wasonly 87%). While this increase may have been due to analyticalvariations at such low concentrations, it appears that the treatment wasconverting some detectable PFAS into other detectable PFAS compounds.PFOS is one such compound that decreased from 320 ppb initially to 0.07ppb (the new EPA Drinking Water Health Advisory level) in nine hours butthen increased to 3.2 ppb at sixteen hours. Regardless, the overallremoval of PFOS was 99%.

PFAS analyzed in three of the exhaust water trap contents showed thatmost of the PFAS that were removed by the sparging exhaust occurred inthe first hour via aerosols and/or foam. Smaller amounts PFAS were alsotransferred via the exhaust during the second hour of oxygenation andduring the third to nine hours of ozonation, presumably via aerosols(since foam was not observed being transferred). Not all the consecutiveexhaust water traps were analyzed for PFAS so the total amount of PFAStransferred was not known. However, the three traps that were analyzeddemonstrated that at least 81 ug of PFAS (mostly PFOS) were transferred.This is approximately 4% of the PFAS that were in the reactor at timezero.

Fluoride concentration increased in the reactor during the 19 hours oftesting, indicating defluorination and release of the organofluorine bythe PFAS. Some of this released fluoride was transferred from thereactor to the off-gas trap via aerosols and/or foam during the firsthour of oxygenation. Smaller amounts of released fluoride continued tobe transferred from the reactor to the off-gas during the subsequent 18hours most likely via aerosols. The total amount of fluoride releasedand found in the reactor (397 ug) and the off-gas water trap (116 ug)was 513 ug or about 42% of the organofluorine contained in the detectedPFAS at time zero (1230 ug).

The following conclusions are drawn from the experiment results:

-   -   Both oxygenated and ozonated buffered persulfate were shown to        remove PFAS from the reactor by both chemical        destruction/defluorination and physical transfer as an aerosol        and/or foam to the off-gas water trap.    -   Overall removal of identifiable PFAS after 19 hours of        oxygenation and ozonation treatment was 87% while many        individual PFAS were removed to below detection limits.    -   42% of the organofluorine in the detected PFAS were        de-fluorinated and released during the test.

Example 5

This experiment was conducted in steam distilled water spiked with PFASto evaluate the removal, degradation and de-fluorination of PFOS andPFOA during treatment with oxygenated buffered persulfate. Theexperiment was specifically designed to evaluate the integratedmechanisms of 1) chemical degradation by oxidation and/or reduction ofPFAS; and 2) transfer of PFAS from buffered persulfate as an aerosol orfoam by sparging pure oxygen gas into phosphate buffered persulfatewater containing PFOS and PFOA. The solution pH was approximately pH9.0.

Procedure

The experiment was conducted in a plastic column reactor with a spargerat the bottom of the reactor that was filled with steam distilled water.Pure oxygen was sparged into the solution at the bottom of the reactor.The off-gas from the column reactor was passed through an off-gas trapto catch any aerosols or foam and ultimately vented to the ambientatmosphere.

The plastic column reactor and the off-gas trap were tested prior to theexperiment to confirm that they did not sorb or desorb fluoride, PFOS,or PFOA. The distilled water used in the testing, as in some of thepreviously described experiments, contained a background concentrationof 3-4 ug/l of fluoride.

To create the test solution, PFOS and PFOA were spiked into 2.3 litersof distilled water, followed by phosphate buffer and persulfate additionat the same concentrations as in previous experiments, to produce a testsolution with a pH between pH 9 and pH 10.

This test solution was analyzed for PFAS, pH, and fluoride andtransferred to the column reactor where pure oxygen was sparged into thesolution at various flowrates and pressures. The fluoride concentrationwas analyzed as explained previously to assess de-fluorination of thePFAS compounds. At various intervals during the 48 hour experiment,samples were collected from the column and off-gas trap for PFASanalysis.

FIG. 3 and Table 5 present the resulting measured concentration of PFASover time. The PFAS consists of PFOS and PFOA plus small concentrationsof six other PFAS believed to be minor contaminants contained within thepurchased PFOS and PFOA chemicals. Only one PFAS,perfluoroheptanesulfonate, was detected greater than 1 ug/l.

TABLE 5 PFAS Experimental Data from Column Reactor 0 hours 1 hour 2hours 48 hours % removal PFAS Concentration of PFAS (micrograms/liter =ppb) . 6:2 Fluorotelomer sulfonate 0.25 <2.1 <0.21 <0.016 96.8%Perfluorobutane Sulfonate (PFBS) 0.32 <2.3 0.30 0.0091 97.2%Perfluorobutanoic acid <200 12 <200 0.10 99.9% Perfluoroheptanesulfonate 6.6 6.3 3.2 0.010 99.8% Perfluoroheptanoic Acid (PFHpA) 0.55<2.7 0.51 <0.012 98.9% Perfluorohexane Sulfonate (PFHxS) 0.78 1.7 0.75<0.010 99.4% Perfluorohexanoic Acid (PFHxA) 0.41 <1.7 0.42 0.016 96.1%Perfluoro-n-Octanoic Acid (PFOA) 250 280 220 0.19 99.9% PerfluorooctaneSulfonate (PFOS) 180 72 23 0.11 99.9% Perfluoropentanoic Acid (PFPeA)<0.21 <2.1 <0.21 0.11 NC Perfluorotetradecanoic Acid <0.20 2.2 <0.20<0.013 NC Perfluoroundecanoic Acid (PFUnA) 0.15 <1.4 <0.14 <0.0093 99.7%TOTAL PFAS (ppb) 439 374 248 0.55 99.9% NC: Not Calculated (due to nodetection in original sample)

As shown in FIG. 3 and Table 5, the concentration of total detected PFASin the column reactor decreased by 99.9% within 48 hours, from 439 ppbto >0.6 ppb. The two added compounds, PFOS and PFOA, had an initialconcentration of 180 and 250 ppb, respectively, which decreased by 99.9%to 0.11 and 0.19 ppb, respectively, during the same time period. Theseconcentrations are less than the 2009 EPA Provisional Health AdvisoryGuidelines of 0.2 and 0.4 ppb, respectively, for PFOS and PFOA. The rateof PFAS concentration decrease in the reactor was most significant inthe beginning of the test.

The initial PFAS mass in the water contained in the column reactor was1,010 micrograms but after the 48 hours of testing and 99.9% removal,only 1 microgram of PFAS remained.

Approximately 26% of the initial 1,010 micrograms of PFAS in the columnreactor (i.e. 260 micrograms) was transferred with the off-gas from thecolumn reactor to the off-gas water trap. Very little PFAS (0.6micrograms) were transferred in the first hour, 18 micrograms (2% of thetotal) in the second hour, with the majority (241 micrograms) of thePFAS transferred between 2 to 48 hours.

The fluoride concentration in the column reactor gradually increasedfrom the initial time zero (i.e., before oxygenation) concentration of17 ug/l to 52 ug/l after 48 hours. The rate of PFAS de-fluorinationresulting in the release of fluoride decreased during the 48 hour test,from 16 micrograms during the first hour, 8 micrograms during the secondhour, 4 micrograms/hour for the next 7.5 hours and 1.6 micrograms/hourthereafter. This indicates that, in addition to the PFAS that wastransferred from the column reactor to the off-gas trap, some of thePFAS in the reactor was de-fluorinated as indicated by an increase influoride anion concentration. Over the 48 hour testing period, the totalamount of fluoride released in the column reactor water was 73micrograms, or about 11% of the theoretical fluorine mass contained inthe initial PFAS.

During the 48 hour test the fluoride concentration in each of the threeoff-gas trap samples also increased from the background concentration of3 ug/l in the distilled water. The rate of fluoride released and/ortransferred to the traps was highest at the beginning of the test with0.3 microgram released during the first hour, 0.8 microgram released inthe second hour, and less than 0.1 microgram released per hour from 2 to48 hours. In total, 4.4 micrograms of fluoride was released into thethree sequential off-gas traps. This is about 1% of all the fluoridecontained in the PFAS at time zero. So in total, together with the 11%fluoride released in the column, about 12% of the organofluorinecontained in the initial PFAS mass was de-fluorinated to fluoride.

Based on these PFAS and fluoride measurements throughout this 48-hourexperiment, the following fluoride mass balance shown in FIG. 4 piechart results shows the disposition of the initial PFAS during theexperiment. The integrated PFAS removal mechanisms of chemicaldegradation and transfer from the liquid phase as shown in the pie chartindicates that:

-   -   0.1% of the initial PFAS was still in the column reactor at the        end of 48-hours    -   26% of the initial PFAS was transferred to the off-gas water        trap;    -   10.7% of the fluorine in initial PFAS was de-fluorinated to        fluoride anion and measured in the column reactor;    -   0.6% of fluorine in the initial PFAS was mineralized to fluoride        anion and measured in the off-gas trap;    -   After 48 hours, the remaining 63% of the PFAS remained in the        column reactor or the off-gas traps as unidentifiable poly- or        per-fluorinated PFAS, or as non-fluorinated breakdown products        of PFAS.

The following conclusions are drawn from the experimental results:

-   -   The oxygenated phosphate buffered persulfate de-fluorinates PFAS        and releases fluoride anion.    -   26% of the PFAS was transferred from the water to the off-gas as        aerosols or foam such that more than 99% of PFOS and PFOA were        removed from the water in the column reactor.    -   A total of 12% of the organofluorine in PFAS was de-fluorinated        to fluoride.

Definitions

“Persulfate” includes both monopersulfate and dipersulfate. Typically,persulfate is in the form of aqueous sodium, potassium or ammoniumdipersulfate or sodium or potassium monopersulfate or a mixture thereof.

As used herein, “phosphate” includes both inorganic and organic forms.It can be supplied as a simple inorganic phosphate in the form of sodiumor potassium dibasic phosphate, or as sodium or potassium monobasicphosphate, or sodium or potassium tribasicphosphate. The simple forms ofphosphate are used as pH buffers. Phosphates can also be supplied ascomplex inorganic phosphate in the form of sodium tripolyphosphate,sodium-potassium tripolyphosphate, tetrasodium polyphosphate, sodiumhexametaphosphate, and sodium trimetaphosphate. These phosphates canalso be used as a phosphate source. In aqueous solution, the hydrolyticstability of the phosphate depends on the original phosphate compound.For example, linear polyphosphates undergo slow hydrolysis. This processcontinues as the shorter chain polyphosphates break down further toyield still shorter chain polyphosphates, metaphosphates, andorthophosphates. Generally, lower pH and higher temperature willincrease the rate of hydrolysis. Long chain polyphosphates will breakdown into shorter, but still functional, polyphosphates. Sodiumtripolyphosphate is a strong cleaning ingredient used in detergents toaid surfactants and act as a pH buffer.

Phosphate can also be supplied as phosphonate, which is an organic formof phosphate containing C-PO(OH)₂ or C-PO(OR)₂ groups (where R=alkyl,aryl). Phosphonates are known as effective chelating agents. Theintroduction of an amine group into the molecule to obtain—NH2-C-PO(OH)₂ increases the metal binding abilities of the phosphonate.Examples for such compounds are EDTMP and DTPMP. These commonphosphonates are the structure analogues to the well-knownaminopolycarboxylates NTA, EDTA, and DTPA. The stability of the metalcomplexes increases with increasing number of phosphonic acid groups.Phosphonates are highly water-soluble while the phosphonic acids areonly sparingly soluble.

In addition, phosphate can also be supplied as a peroxodiphosphate orperphosphate, which is a peroxide form of phosphate. It is known to formradicals when activated and reacted with organic compounds similarly topersulfate. As the perphosphate radical reacts with organic compounds,it decomposes to perphosphate anions. The rate of reaction with organiccompounds is usually much slower compared to persulfate.

When a phosphate will be added to any water that can be potentially usedfor drinking water, there are approved phosphate compounds that can beadded. According to the National Sanitation Foundation, phosphateproducts for supply of phosphate in potable water conditions can bebroadly classified as: phosphoric acid, orthophosphates, and condensedphosphates. These are listed here in detail:

1) Phosphoric Acids

2) Orthophosphates: Monosodium Phosphate (MSP), Disodium Phosphate(DSP), Trisodium Phosphate (TSP), Monosodium Phosphate (MKP),Dipotassium Phosphate (DKP), Tricalcium Phosphate (TCP)

3) Condensed Phosphates: Sodium Acid Pyrophosphate (SAPP), SodiumTrimetaphosphate (STMP), Tetrasodium Pyrophosphate (TSPP), SodiumTripolyphosphate (STP) and Tetrapotassium Pyrophosphate (TKPP), SodiumHeaxametaphosphate (SHMP).

In addition to the use of phosphates for buffering, reactionenhancement, and radical formation in organic chemical reactions,phosphates also play an important role in soluble metal sequestrationand they can form metal precipitates. Phosphate sequestration of metalsis a chemical combination of a phosphate chelating agent and metal ionsin which soluble complexes are formed. Sequestration is dependent uponpH and a given sequestrant typically works best within a certain pHrange. Sodium hexmetaphosphates (SHMP) performs well at neutral pHranges, while pyrophosphates and polyphosphates work best under alkalineconditions. Phosphate can be used to precipitate unwanted metals, suchas lead, from aqueous solution. For example, phosphate forms alead-phosphate precipitate at an optimal pH around pH 6.0. Phosphate canunder certain conditions also react with native metals in a soil/waterenvironment to render the metals non-reactive with any reagentsintroduced into this environment.

The simple phosphates used as pH buffers are added in concentrationranges from 1 gram per liter (g/l) to 15 g/l in a pH range from pH 4 topH10. The complex phosphates can be supplied at 1 g/l to 15 g/l in a pHrange from pH 4 to pH 10. Phosphate compounds can be addedsimultaneously or sequentially with the other reagents.

Phosphate compounds can be mixed with other liquid oxidants, such assodium persulfate and hydrogen peroxide, and then injected to remediatecontaminated soil and groundwater. Phosphate compounds can also bedissolved in water and injected by themselves, to bolster treatment zonepH, to activate oxidants, to complex and isolate metals found in thesoil formation, and to act as a nutrient source for bioremediationpurposes.

These phosphate compounds can be mixed with each other or the otheroxidants. Phosphate radical (e.g. HPO4r-) is produced from unactivatedphosphate species in the presence of ozone through a multi-step process.First, dissolved ozone reacts with hydroxyl anion in solution to formperhydroxyl anion (HO2-). Ozone then reacts with perhydroxyl anion toform superoxide radical and hydroxyl radical. Phosphates scavenge thehydroxyl radical to produce a phosphate radical species. This phosphateradical can then activate persulfate anion to form sulfate radical.

Example Persulfate activation pathway:

O3+OH-−>HO2r-+O2

O3+HO2r-−>O2r-+OHr+O2

HPO4-2+OHr−>HPO4-+OH—

HPO4r-+S2O8-2−>HPO4-2+SO4-2+SO4r

There are known to be other phosphate species such as HPO3r-radical thatcan react similarly with persulfate anion to produce sulfate radical.

Several phosphate species, such as peroxydiphosphate (P208-4), willdecompose to form phosphate radical species (i.e. PO4r-2). Using anoxidizing form of phosphate like this can avoid the initial activationmechanism involving hydroxyl radical scavenging in order to activatepersulfate anion, while still providing buffering capacity afterpersulfate activation has occurred. Additionally, ozone can then be usedto reactivate the spent phosphate for further persulfate anionactivation.

Possible reaction pathway: P2O8-4−>2PO4r-2

PO4r-2+S2O8-2−>PO4-3+SO4-2+SO4r

Which then continues like the persulfate activation pathway above.

“Oxygen” includes all forms of gaseous, liquid, and solid oxygen such aspure oxygen gas, air, hydrogen peroxide, and all other inorganicperoxides such as calcium or magnesium peroxide or organic peroxides,such as organic peroxides available from Luperox.

“Salt” includes sodium chloride and other species having both cationicor cationizable components and anionic or anionizable components.

“Oxidizing radicals” includes sulfate radical, hydroxyl radical,hydroperoxide, phosphate radical and others.

“Reducing radicals” includes superoxide.

“Saturated zone” refers to the region of the soil profile that isconsistently below ground water level.

“Unsaturated zone” refers to the region of the soil profile that isconsistently above ground water level.

“Smear zone” refers to the region of the soil profile through which theground water level fluctuates, typically on a seasonal basis. The smearzone is the region that when the ground water is at its highest would beconsidered saturated and when the ground water is at its lowest would beconsidered unsaturated. It is also called the capillary zone.

“Organic contaminant” is an organic compound that is not native to thesoil or water in which it is found. Organic compounds may include, forexample, poly- and perfluoralkyl compounds (PFAAs), hydrocarbon-basedfuels, halogenated and non-halogenated solvents, pesticides, herbicides,PCBs, volatile hydrocarbons, semi-volatile hydrocarbons, chlorinatedvolatile hydrocarbons, BTEX and MTBE.

“Area or Radius of influence” describes the area around a well or otherinjection point defining an area throughout which an adequate amount ofreactant can be introduced to oxidize at least some of the organiccontaminant present.

While several embodiments of the present invention have been describedand illustrated herein, those of ordinary skill in the art will readilyenvision a variety of other means and/or structures for performing thefunctions and/or obtaining the results and/or one or more of theadvantages described herein, and each of such variations and/ormodifications is deemed to be within the scope of the present invention.More generally, those skilled in the art will readily appreciate thatall parameters, dimensions, materials, and configurations describedherein are meant to be exemplary and that the actual parameters,dimensions, materials, and/or configurations will depend upon thespecific application or applications for which the teachings of thepresent invention is/are used.

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments of the invention described herein. It is, therefore, to beunderstood that the foregoing embodiments are presented by way ofexample only and that, within the scope of the appended claims andequivalents thereto, the invention may be practiced otherwise than asspecifically described and claimed. The present invention is directed toeach individual feature, system, article, material, kit, and/or methoddescribed herein. In addition, any combination of two or more suchfeatures, systems, articles, materials, kits, and/or methods, if suchfeatures, systems, articles, materials, kits, and/or methods are notmutually inconsistent, is included within the scope of the presentinvention. All definitions, as defined and used herein, should beunderstood to control over dictionary definitions, definitions indocuments incorporated by reference, and/or ordinary meanings of thedefined terms.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that 20 are conjunctively present in somecases and disjunctively present in other cases. All references, patentsand patent applications and publications that are cited or referred toin this application are incorporated in their entirety herein byreference.

What is claimed is:
 1. A method of removing poly and/or per fluorinatedalkyl hydrocarbons (PFAS) from water, the method comprising: passinggaseous bubbles through an aqueous phase contaminated with a contaminantcomprising PFAS; transferring at least a portion of the contaminant to aheadspace above the aqueous phase; irradiating the headspace withultraviolet light; and destroying the contaminant.
 2. The method ofclaim 1, wherein the aqueous phase further comprises an oligosaccharide.3. The method of claim 2, wherein the oligosaccharide comprisescyclodextrin.
 4. The method of claim 1, wherein the contaminant isoxidized by adding an oxidizing agent.
 5. The method of claim 1, whereinthe contaminant is reduced by adding a reducing agent.
 6. The method ofclaim 1, further comprising adding an oxidizing agent and a reducingagent sequentially.
 7. The method of claim 1, further comprising addingan oxidizing agent and a reducing agent simultaneously.
 8. The method ofclaim 1, wherein the gaseous bubbles comprise at least one of ozone,nitrogen, nitrous oxide, oxygen and air.
 9. The method of claim 8,wherein the gaseous bubbles comprise microbubbles or nanobubbles. 10.The method of claim 1, further comprising hydrodynamic cavitation. 11.The method of claim 1, further comprising adding a salt to the aqueousphase.
 12. The method of claim 4, further comprising adding at least oneof oxygen, ozone, hydrogen peroxide, inorganic peroxides, persulfate,permanganate and percarbonate to the water.
 13. The method of claim 5,further comprising adding at least one of cyclodextrin, hydrogen, iron,zero valent iron, ferrous sulfate, sulfur dioxide, hydrogen sulfide,dithionate, thiosulfate, iodinites, hydrogen peroxide, oxalic acid,formic acid, ascorbic acid, vitamin B12, reducing sugars, sulfites,phosphites and hypophosphites to the water.
 14. The method of claim 1,further comprising introducing at least one of an activator, a catalyst,a complexing agent, a surfactant, and a co-solvent to the aqueous phase.15. The method of claim 1, wherein the headspace is pressurized.
 16. Themethod of claim 1, wherein vacuum is applied to the headspace.
 17. Themethod of claim 1, wherein at least one of ozone, nitrogen, nitrousoxide, oxygen and air is applied to the headspace.
 18. The method ofclaim 1, wherein the PFAS is an aerosol in the headspace.